5.1) Defence mechanisms Flashcards
What is a pathogen?
A microorganism that causes disease
What are the two forms of specific immune responses?
Cell-mediated responses and humoral responses
Cell-mediated responses involve T lymphocytes; humoral responses involve B lymphocytes.
Why is immunity important after an infection?
The body’s defences are better prepared for a second infection from the same pathogen
This preparedness allows for quicker and more effective responses.
What factors influence the effectiveness of the body’s defence mechanisms?
- Overall state of health
- Age
- Fitness level
Fit adults rarely die from infections; the young and elderly are more vulnerable.
How do lymphocytes distinguish between self and non-self cells?
By specific molecules on their surface, mainly proteins
Proteins have a highly specific tertiary structure that allows for identification.
What types of threats can the immune system identify?
- Pathogens
- Non-self material
- Toxins
- Abnormal body cells
Examples include HIV, cells from other organisms, cholera toxins, and cancer cells.
What happens if lymphocytes cannot distinguish self from non-self?
They would destroy the organism’s own tissues
This could lead to autoimmune diseases.
What is clonal selection in the immune response?
The process where a specific lymphocyte is stimulated to divide in response to a pathogen
This builds up the lymphocyte numbers to effectively combat the infection.
How many different types of lymphocytes are estimated to exist?
Approximately ten million
Each type can recognize a different chemical shape.
What occurs to lymphocytes that react to self-antigens?
They undergo programmed cell death (apoptosis)
This prevents the development of anti-self lymphocytes.
What is the role of immunosuppressant drugs in organ transplants?
To reduce the level of the immune response against the transplant
These drugs help minimize tissue rejection.
What is the significance of the tertiary structure of proteins in the immune system?
It allows for the identification of self versus non-self cells
The variety in protein structure is important for immune recognition.
What is a self cell?
The body’s own cells and molecules
What is a non-self (foreign) cell?
Not your own body’s cells and molecules
